1. Field of Invention
The present invention relates to a yarn containing filaments made from synthetic polymers with a cross-section having at least 5 vertices.
2. Description of Related Art
Yarns of this type have been used in the manufacture of textiles and carpets to improve the appearance of the textiles and carpets. In the manufacture of textile fabrics such as wovens, knitted and crocheted fabrics and nonwovens from yarns containing synthetic polymer filaments, it is observed that the fabrics produced show a luster that is often not wanted. The filaments of these yarns therefore often contain matting agents. The luster in textile fabrics can be further reduced by using yarns with a profiled cross-section. Thus in EP 0 605 333, for example, filaments with matting agents and having a multilobal cross-section containing at least 5 lobes are used to manufacture carpets, the filaments in the finished carpet having good crimp shape retainability and no luster. The filaments have an individual titer of 20 dtex.
Luster is of little importance in the manufacture of woven technical fabrics, particularly airbag fabrics. The most important consideration in the manufacture of these fabrics is the use of yarns with filaments having high tenacity and guaranteeing good foldability. Yarns of high tenacity and low individual titer are therefore preferred. Because it has always been assumed by those skilled in the art that yarns with filaments having a profiled cross-section are of lower tenacity than those with filaments of round cross-section, the former have always been regarded as unsuitable for use in woven technical fabrics.
Polyester yarns, particularly polyamide yarns such as nylon 4, nylon 4,6 and especially nylon 6,6, are suitable for manufacturing woven technical fabrics. The finished fabrics should have very low air permeability, particularly in the case of airbag fabrics. The air permeability of these fabrics can be further reduced by coating them, e.g., with silicone, after manufacture. Coating the fabrics is not easy, however, as a coating often does not readily adhere to the highly developed filaments of the yarns used.
The object of the present invention is to provide a yarn in which the above-mentioned disadvantages in the manufacture and use of technical fabrics, and particularly airbag fabrics, are significantly reduced.
The object is achieved with a yarn containing filaments of synthetic polymers having a cross-section with at least 5 vertices, a titer between 1 and 7 dtex and a tenacity of at least 60 cN/tex.
It has been shown that woven fabrics produced from yarns of this type have intrinsically lower air permeability than those produced from yarns comprising filaments of round or oval cross-section, and also show significantly improved adhesion properties for coating materials. It was also surprisingly found that yarns comprising filaments of which the cross-section has a number of vertices can be manufactured so as to have high tenacity.